This invention relates to a self-extinguishing blanket.
This invention relates particularly to a self-extinguishing blanket of the kind which is positioned between the inner and outer skin of the fuselage of an airliner. The self-extinguishing blanket incorporates a heat insulating layer of lass fiber strands sandwiched between two outer strand reinforced plastic films. The films serve primarily as moisture barriers for preventing entry of moisture into the dry air spaces of the insulating layer of glass fiber strands.
This invention relates particularly to a composition and construction of the self-extinguishing blanket which enables a portion of the plastic film, when subjected to a direct flame or to the heat developed by an adjacent flame, to soften, to pull apart and to shrink and curl back sufficiently far so as to prevent heating of that portion of the plastic film to the ignition temperature. This shrinking and curl back of the plastic film minimizes the chance of ignition of the plastic film and prevents propagation of the flame through the plastic film. The composition and construction provide a self-extinguishing blanket.
There are a number of applications requiring a self-extinguishing insulation blanket of the kind which will (1) provide insulation against heat transfer and (2) also provide resistance to rips or tears occurring during normal fabrication and/or installation and (3) also be self-extinguishing in the event of exposure to a direct flame or the heat from an adjacent flame.
An insulation blanket installed between the inner and outer skins of an airliner particularly requires a self-extinguishing blanket of this kind.
Because there is a large temperature gradient which must be maintained between the air temperature outside an airliner and the cabin temperature within the airliner, the insulation between the inner and outer skins of an airliner must provide a high degree of insulation against the transfer of heat between the inner and outer skins of the airliner. A layer of glass fiber strands is used as the main heat insulation component for such applications because the glass fiber strands provide air spaces between the strands. The air spaces are effective to provide a high degree of insulation against heat transfer so long as the air spaces are kept dry. Moisture condenses on the inside surface of the outside skin of an airliner. This condensed moisture can degrade the heat insulation qualities of the layer of glass fibers if the moisture and/or condensed moisture can find a way into the air spaces between the glass fiber strands.
Thin plastic films are used to cover and to sandwich the glass fiber strands between the films. The films serve as barriers to the entry of moisture into the insulating layer of glass fiber strands. The thickness of each film is kept as small as possible in order to minimize weight, and strand reinforcement is applied to the plastic film to add strength to the film. The strand reinforcement also limits the effects of punctures, tears or rips in the plastic film. Rips and tears occur during the sewing, or other connecting together, of peripheral edge portions as required to produce a pre-configured blanket package for fitting into a particular location on an airliner fuselage. Rips and tears can also occur during the actual installation of the blanket package into such locations on the airliner.
The plastic films must be adhered to the insulating layer to prevent shifting of the film laterally and longitudinally of the insulating layer during the fabrication (e.g. the sewing together of the peripheral edge portions) required to produce a pre-configured blanket package product for a specific location on the airliner.
The plastic films have been attached to the insulating layer by laminating and by stitching.
Laminating has included the use of a laminating adhesive which attaches the entire inner surface of the plastic film to the adjacent surface of the insulating layer of glass fiber strands.
The stitching has included stitching entirely through the sandwiched structure at certain lines or areas of the sandwiched structure.
These existing means of attachment have served the purpose of holding the plastic films in place during peripheral edge sewing or other connection as required for the manufacture of a selected, peripheral configuration of a blanket package product, but these means of attachment have presented problems in the event the blanket is subjected to a direct flame or to the heat of a closely adjacent flame as may occur in the event of a crash of the airliner and the spill of engine fuel as a result of the crash.
The laminating means of attachment have, in such events, functioned to hold the plastic film so firmly in place that the film itself catches on fire and propagates the flame by means of the fuel (the carbon and hydrogen composition) provided by the plastic film itself. The stitching means of attachment have allowed moisture to enter into the insulating layer of glass fiber strands by perforating the plastic film.
It is a primary object of the present invention to construct a self-extinguishing blanket with minimum or no perforation of the plastic film.
It is a related object of the present invention to construct a self-extinguishing blanket which avoids the problems of flammability present in prior art blanket constructions.